XmDisplay

NAME

XmDisplay — The Display widget class "XmDisplay" "widget class" "XmDisplay"

SYNOPSIS

#include <Xm/Display.h>

DESCRIPTION

The XmDisplay object is used by the Motif widgets to store information that is specific to a display. It also allows the toolkit to access certain information on widget hierarchies that would otherwise be unavailable. Each client has one XmDisplay object for each display it accesses. An XmDisplay object is automatically created when the application creates the first shell on a display (usually accomplished by a call to XtAppInitialize or XtAppCreateShell). It is not necessary to create an XmDisplay object by any other means. An application can use the function XmGetXmDisplay to obtain the widget ID of the XmDisplay object for a given display. An application cannot supply initial values for XmDisplay resources as arguments to a call to any function that creates widgets. The application or user can supply initial values in a resource file. After creating the first shell on the display, the application can use XmGetXmDisplay to obtain the widget ID of the XmDisplay object and then call XtSetValues to set the XmDisplay resources. XmDisplay resources specify the drag protocol style for a client participating in drag and drop transactions. The two basic protocol types are preregister and dynamic. When a preregister protocol is used, the toolkit handles any communication between the initiator and receiver clients and displays the appropriate drag-over and drag-under visual effects. A client registers its drop sites in advance and this information is stored in a property for each top-level window. When the drag pointer enters a top-level window, the drop site information is read by the initiator. A dynamic protocol allows the source and destination clients to dynamically communicate drag and drop state information between each other, and to update their respective visuals accordingly. The toolkit provides drop site information as the pointer passes over any given drop site. In this mode, a receiver can supply a procedure to generate its own drag-under effects.

Classes

Display inherits behavior and resources from Core, Composite, Shell, WMShell, VendorShell, TopLevelShell, and ApplicationShell classes. The class pointer is xmDisplayClass. The class name is XmDisplay.

New Resources

The following table defines a set of widget resources used by the programmer to specify data. The programmer can also set the resource values for the inherited classes to set attributes for this widget. To reference a resource by name or by class in a .Xdefaults file, remove the XmN or XmC prefix and use the remaining letters. To specify one of the defined values for a resource in a .Xdefaults file, remove the Xm prefix and use the remaining letters (in either lowercase or uppercase, but include any underscores between words). The codes in the access column indicate if the given resource can be set at creation time (C), set by using XtSetValues (S), retrieved by using XtGetValues (G), or is not applicable (N/A).

XmDisplay Resource Set
Name	Class	Type	Default	Access
_	_	_	_	_
XmNdefaultButtonEmphasis	XmCDefaultButtonEmphasis	XtEnum	XmEXTERNAL_HIGHLIGHT	C
_	_	_	_	_
XmNdefaultVirtualBindings	XmCDefaultVirtualBindings	String	dynamic	C
_	_	_	_	_
XmNdragInitiatorProtocolStyle	XmCDragInitiatorProtocolStyle	unsigned char	XmDRAG_PREFER_RECEIVER	CG
_	_	_	_	_
XmNdragReceiverProtocolStyle	XmCDragReceiverProtocolStyle	unsigned char	XmDRAG_PREFER_DYNAMIC	CG
_	_	_	_	_
XmNdragStartCallback	XmCCallback	XtCallbackList	NULL	C
_	_	_	_	_
XmNenableBtn1Transfer	XmCEnableBtn1Transfer	XtEnum	XmOFF	C
_	_	_	_	_
XmNenableButtonTab	XmCEnableButtonTab	Boolean	False	C
_	_	_	_	_
XmNenableDragIcon	XmCEnableDragIcon	Boolean	False	C
_	_	_	_	_
XmNenableEtchedInMenu	XmCEnableEtchedInMenu	Boolean	False	C
_	_	_	_	_
XmNenableToggleColor	XmCEnableToggleColor	Boolean	False	C
_	_	_	_	_
XmNenableToggleVisual	XmCEnableToggleVisual	Boolean	False	C
_	_	_	_	_
XmNenableUnselectableDrag	XmCEnableUnselectableDrag	Boolean	True	C
_	_	_	_	_
XmNenableWarp	XmCEnableWarp	XtEnum	True	CSG
_	_	_	_	_
XmNmotifVersion	XmCMotifVersion	int	XmVERSION	CSG
_	_	_	_	_
XmNnoFontCallback	XmCCallback	XtCallbackList	NULL	C
_	_	_	_	_
XmNnoRenditionCallback	XmCCallback	XtCallbackList	NULL	C
_	_	_	_	_
XmNuserData	XmCUserData	XtPointer	NULL	CSG
_	_	_	_	_

XmNdefaultButtonEmphasis

Specifies whether to change the look of the PushButton widget and gadget that have the XmNshowAsDefault resource set. When the PushButton is the default, it has an etched out button which is enclosed with another etched in border. The XmNdefaultButtonEmphasis has the follow possible values, which affect the location cursor:

XmNdefaultVirtualBindings

Specifies the default virtual bindings for the display. Following is an example of a specification for the defaultVirtualBindings resource in a resource file:

*defaultVirtualBindings: \
        osfBackSpace:       <Key>BackSpace       \n\
        osfInsert:       <Key>InsertChar      \n\
        osfDelete:       <Key>DeleteChar      \n\
        ...
        osfLeft:       <Key>left, Ctrl<Key>H

XmNdragInitiatorProtocolStyle

Specifies the drag and drop protocol requirements or preference when the client is an initiator. The possible values are

XmNdragReceiverProtocolStyle

Specifies the drag and drop protocol requirements or preference when this client is a receiver. The values are

The default value of this resource is dependent on the capabilities of the display. If the display supports the shape extension, allowing the dynamic protocol to use arbitrarily sized drag cursors, the default of this resource is XmDRAG_PREFER_DYNAMIC, otherwise the default is XmDRAG_PREFER_PREREGISTER.

The actual protocol used between an initiator and a receiver is based on the protocol style of the receiver and initiator. The decision matrix is described in the following table.

Drag Initiator
	Drag Receiver Protocol Style
	_	_	_	_	_
	Preregister	Prefer Preregister	Prefer Dynamic	Dynamic
	_	_	_	_	_
	Preregister	Preregister	Preregister	Drop Only
	_	_	_	_	_
	Preregister	Preregister	Preregister	Dynamic
	_	_	_	_	_
	Preregister	Preregister	Dynamic	Dynamic
	_	_	_	_	_
	Preregister	Dynamic	Dynamic	Dynamic
	_	_	_	_	_
	Drop Only	Dynamic	Dynamic	Dynamic

The value XmDRAG_NONE does not appear in the matrix. When specified for either the initiator or receiver side, XmDRAG_NONE implies that drag and drop transactions are not supported. A value of XmDRAG_DROP_ONLY (Drop Only) results when an initiator and receiver cannot compromise protocol styles, that is, one client requires dynamic mode while the other can only support preregister mode, or if either explicitly has specified XmDRAG_DROP_ONLY.

XmNdragStartCallback

Specifies the list of callbacks that are invoked when the XmDragStart function is called. The type of structure whose address is passed to this callback is XmDragStartCallbackStruct. The callback reason is XmCR_DRAG_START.

XmNenableBtn1Transfer

Specifies if selection and transfer actions are integrated on Btn1 and extend actions are activated on Btn2. This resource can take the following values:

This resource affects the actions of Text, TextField, List, and Container.

XmNenableButtonTab

Specifies if the action for the <Tab> key (KNextField and KPrevField actions) is to be modified. A value of True modifies the key to move as an arrow key until the boundary of a tab group is reached. Then, at the boundary of the tab group, KNextField and KPrevField will move to the next or previous tab group, respectively. A value of False does not cause modification.

XmNenableDragIcon

Specifies which set of icons are to be used for system default cursors during drag and drop operations. A value of False specifies that earlier versions of Motif release icons are used, a value of True specifies that alternate icons are used. This resource affects both the 16x16 and the 32x32 icons that the system defaults for each of the Screen objects associated with this display.

XmNenableEtchedInMenu

Specifies the shadowing of the button widgets and gadgets in menus when the control is activated. A value of True causes the selected menu to be drawn with the shadow etched in; this shadow style is consistent with the selected appearance of other button widgets outside of menus. A value of False causes the selected menu to be draw with the shadow etched out. This resource affects the actions of PushButton, ToggleButton, and CascadeButton widgets and gadgets when they are children of Menu.

When this resource is set, the background of a button in a menu uses the XmNselectColor (derived from the XmNselectPixel) when armed as a default. A PushButton uses the XmNarmColor if it is defined. A ToggleButton uses the XmNselectColor if XmNindicatorOn is False and XmNfillOnSelect is True.

XmNenableToggleColor

Specifies how to determine the default value of the XmNselectColor resource of ToggleButton and ToggleButtonGadget. A value of True causes the default value of XmNselectColor to be set to the value of XmNhighlightColor. A value of False causes the default value of XmNselectColor to be set to the value of XmNbackground. This resource only affects the appearance of ToggleButton widgets and gadgets that are in XmONE_OF_MANY or XmONE_OF_MANY_ROUND mode. In addition, XmNenableToggleColor only influences the default value of XmNselectColor. That is, if the user or application sets a value for XmNselectColor, then XmNenableToggleColor is ignored.

XmNenableToggleVisual

Specifies the visual appearance of the ToggleButton widget and/or gadget. This resource affects the default value of the ToggleButton[Gadget] XmNindicatorType and XmNindicatorOn resources. When the ToggleButton is in a RadioBox, a value of True causes the XmONE_OF_MANY_ROUND (a shadowed circle) to be the default. Otherwise, when this resource is True, the ToggleButton XmNindicatorOn resource causes a default of XmN_OF_MANY, which will be a shadowed square with a check mark (check box).

A value of False causes the following:

XmNenableUnselectableDrag

Specifies whether or not it is possible to drag from Label and Scale. A value of True enables the drag; a value of False disables it.

XmNenableWarp

Specifies if an application is allowed to warp the pointer from the user. A value of True enables warping, a value of False does not.

XmNmotifVersion

Specifies the current version of Motif that the current implementation is supposed to behave like. By default, this resource gets its value from release values in Xm.h.

XmNnoFontCallback

This callback is called whenever a rendition attempts to load a font or fontset and fails. This can happen on creation if the font is specified as XmLOAD_IMMEDIATE or when an attempt is made to render an XmString using a font specified as XmLOAD_DEFERRED. An application can have this callback attempt to remedy this problem by calling XmRenditionUpdate on the input rendition to provide a font for the widget to use. This may be done by either providing an an alternative font name to be loaded using the XmNfontName and XmNfontType resources or with an already loaded font using the XmNfont resource. The callback reason is XmCR_NO_FONT. This callback uses the XmDisplayCallbackStruct structure.

XmNnoRenditionCallback

This callback is called whenever an attempt is made to render a segment with a RENDITION tag which does not match any renditions in a given render table. The callback reason is XmCR_NO_RENDITION. This callback uses the XmDisplayCallbackStruct structure.

An application can have this callback attempt to remedy this problem by creating a new rendition with the given tag and adding it to render_table.

The XmNnoRenditionCallback should deallocate the render table passed in in the render_table field of the callback structure. Note that the table will automatically be deallocated if the XmRenderTableAddRenditions function is called on it. The callback should NOT deallocate the modified render table that is passed back to Motif in the render_table field. If the application wishes to manipulate this render table further, it should make a copy with the XmRenderTableCopy function before returning from the callback.

XmNuserData

Specifies a client data pointer for applications. An internally unused resource.

Inherited Resources

All of the superclass resources inherited by XmDisplay are designated N/A (not applicable).

Callback Information

A pointer to the following structure is passed to the XmNdragStartCallback callback:

typedef struct
{
        int  reason;
        XEvent  * event;
        Widget  timeStamp;
        Boolean  doit;
}XmDragStartCallbackStruct;

reason

Indicates why the callback was invoked

event

Points to the XEvent that triggered the callback

widget

Indicates the ID of the widget from which the drag was initiated.

doit

Is an IN/OUT member that allows the callback to determine whether to continue with the drag or cancel. Setting doit to False will cancel the drag. The default value is NULL.

A pointer to the following structure is passed to the XmNnoFontCallback and XmNnoRenditionCallback callbacks:

typedef struct
{
        int  reason;
        XEvent * event;
        XmRendition  rendition;
        char * font_name;
        XmRenderTable  render_table;
        XmStringTag  tag;
}XmDisplayCallbackStruct;

reason

Indicates why the callback was invoked.

event

Points to the XEvent that triggered the callback. It can be NULL.

rendition

Specifies the rendition with the missing font.

font_name

Specifies the name of the font or font set which could not be loaded.

render_table

Specifies the render table with the missing rendition.

tag

Specifies the tag of the missing rendition.

The following table describes the reasons for which the individual callback structure fields are valid.

Reason	Valid Fields
_	_
XmCR_NO_FONT	rendition, font_name
_	_
XmCR_NO_RENDITION	render_table, tag
_	_

RELATED

ApplicationShell(3), Composite(3), Core(3), TopLevelShell(3), VendorShell(3), WMShell(3), XmGetXmDisplay(3), and XmScreen(3).